The invention relates to a process for the filling of receptacles with doughy filling material by means of a filling head, which is provided with an outlet opening for the filling material, the receptacle to be filled being moved upwardly, along a vertical axis which it has in common with the filling head, into a position in which the receptacle bottom is at or close to the filling head and the filling material then being pressed out of the filling head and into the receptacle under the action of a pressing force while the receptacle is simultaneously returned in a relative movement from the filling head.
The invention relates furthermore to a device for carrying out this process.
A process and a device of this mentioned type are e.g. described in the DE-OS 19 38 298, the DE-OS 30 41 885, the DE-OS 31 35 244, the U.S. Pat. No. 3,124,916 and the U.S. Pat. No. 3,172,435. The devices known from this prior art use a nozzle as filling head onto which the receptacle to be filled can be slipped with little clearance and whose outlet opening corresponds substantially to the cross-section of the receptacle to be filled or the receptacle bottom as regards shape and size. The filling material to be filled in is located in a feeding reservoir connected to the nozzle by a pipeline. The filling material is acted upon with a certain pressing out force in this feeding reservoir and supplied thereby to the nozzle via the pipeline. This pressing out force must not exceed a maximum value, because otherwise the filling material pressed into the receptacle gushes out between the receptacle wall and the filling head.
This arrangement leads in particular in the case of viscous pastelike and inhomogeneous filling material such as e.g. lumpy and/or fibrous filling material with non-uniform density distribution as well as air inclusions to the fact that the limited pressing out pressure exerted in the feeding reservoir is transmitted through the inhomogeneous filling material strand to the receptacle bottom in a non-uniform manner, this being a result of the filling material having a relatively great length and a comparatively large diameter in accordance with the nozzle cross-section. Consequently, the non-uniform density distribution is also maintained in the filling material strand pressed into the receptacle and air inclusions are only insufficiently removed. However, air inclusions lead to a premature spoiling of the receptacle content and also to an over-charging of the receptacle so that filling material protrudes and the closing of the receptacle is rendered difficult. In particular in the case of receptacles with a continuous edge flange, onto which a cover is to be sealed, an over-charging of the receptacle and thus a soiling of the edge flange means an insufficient tightness of the sealing closure. Also in this case the content of the receptacle can be spoiled prematurely.
A further disadvantage of a filling head known from the prior art in the form of the aforementioned nozzle consists in that due to the spatial conditions the nozzle cannot be equipped with a cutting means for separating the filling material strand after the completion of the filling process. A separation of the filling material strand is e.g. effected in the device known from the U.S. Pat. No. 3,124,916 by a movement of the filled receptacle transversely to the nozzle to shear off the filling material filled in from the filling material strand leaving the nozzle. It is disadvantageous here that in particular in the case of viscous pastelike and sticky filling material such material is withdrawn from the area of the receptacle being in front in the direction of movement and accumulates in the rear area in the form of a bead of material, a soiling of the edge flange of the receptacle by the bead of material not being excluded. To avoid this the receptacle is for instance rotated about its axis by 180.degree. after the shearing off of the filling material strand in the device known from the U.S. Pat. No. 3,172,435 so that the bead of material gets into the front area of the receptacle, is taken by the cover upon the closing of the receptacle and pressed back into the receptacle. Also here the spilling of filling material over the sides of the receptacle and the soiling of the receptacle edge cannot be excluded. The DE-OS 31 35 244 suggests on the other hand to control the distance of the receptacle from the nozzle during the shearing off so that initially the filling material is sheared off at a level above the upper edge of the receptacle and that subsequently after the reduction of the distance between the receptacle and the nozzle the rear upper edge of the receptacle wipes across the lower edge of the nozzle. Apart from the considerable constructional and control-technique expenditure for this control, soilings of the upper edge of the receptacle can neither be excluded here, in particular because the shearing level is not exactly defined. Moreover there is in general the risk during the shearing off of the filling material strand that the side of the nozzle being in front in the direction of the shearing movement is also soiled and that due to this soiling the upper edges of empty receptacles introduced into the device are also soiled.
A filling machine for viscous filling material is known from the DE-OS 23 30 699, whose filling head almost filling up the cross-section of the receptacle has an outlet opening which corresponds to about half the cross-sectional surface of the filling head and thus makes the use of a cutting means in the form of a knife and a counter-knife at the filling head possible. However, this known filling machine has the disadvantage that the filling head remains completely within the space enclosed by the receptacle during the actuation of the cutting means so that the receptacle cannot be completely filled and thus not be closed without air inclusions. A further disadvantage consists in that during the filling operation the distance between the filling head and the receptacle bottom is not changed as opposed to the process of the genus so that there is the risk during the filling in of in particular viscous pastelike filling material that the filling material strand filled only into one half of the cross-section of the receptacle tilts over in the direction of the non-filled half of the cross-section of the receptacle when a certain height in the receptacle is reached and thus includes air. Since the cross-section of the filling material strand corresponds to about half the cross-section of the receptacle bottom, the included air cannot escape through the overturned part of the filling material strand. Thus in this device which is of another genus the same disadvantages caused by air inclusions occur as in the prior art according to the genus.